The present invention relates to an air bearing slider carrying a transducing head in a disc drive. More particularly, it relates to flushing lubricant from the slider that has accumulated on the slider.
Air bearing sliders have been extensively used in disc drives to appropriately position a transducing head above a rotating disc. In many high capacity storage applications, when the disc is at rest, the air bearing slider is in contact with the disc. During operation, the disc rotates at high speeds, which generates a relative flow of air immediately adjacent the flat surface of the disc. The relative flow of air acts upon the lower air bearing surface of the slider and generates a pressurization profile that causes the slider to fly at an ultra-low fly height above the disc. A slider is typically mounted on a suspension comprising a gimbal and load beam assembly which biases the slider toward the rotating disc, providing a preload force opposite to the lift force acting on the air bearing surface of the slider. In negative pressure sliders, the relative flow of air also acts upon a portion of the air bearing surface of the slider to generate a suction force. The suction force counteracts the lift force by pulling the slider back toward the surface of the disc. For the slider to maintain a stable flying height above the surface of the disc, the lift force must be balanced with the preload and suction forces.
As disc storage systems are designed for increased storage capacities, the density of concentric data tracks on the disc increases (that is, the size of data tracks and radial spacing between data tracks decreases). Reduced fly height is one aspect of achieving higher data storage densities. Furthermore, increased data storage density requirements has resulted in a decrease in the air bearing gap, or head media spacing (HMS) between the transducing head carried by the slider and the rotating disc. As HMS has decreased and data storage densities have increased, accumulation of lubricant (lube) on the slider has become an increasing problem and frequent cause of eventual interface failure and slider crashing upon extended device operation.
Lubricant is typically applied to the disc to prevent corrosion. Additionally, lubricant aids in protecting the slider, the transducing head, and the disc from being damaged during intermittent contact between the slider and the disc. Lubricant displaced from the disc by evaporation or head disc contact may collect on the slider body. The collected lube typically migrates across the surface of the slider and accumulates in a location where airflow across the slider tends to produce a stagnation point. Trenches or other features maybe included in the slider to generate lift force or alter the pressurization profile. Such features may create regions of air flow stagnation and are a common location for lubricant accumulation. Lubricant accumulation in the trenches changes the contours of the slider and may induce a loss of fly height. A loss of fly height leaves the slider more susceptible to media-topography induced fly modulation and may result in increased intermittent contact between the slider and the disc. This process results in further lubricant accumulation and additional fly height loss. Cumulative fly height loss results until eventually the slider crashes.
The progressive accumulation of lubricant within the trenches induces a loss of fly height and increased modulation resulting in interface failure and slider crashing into the media. There is a need in the art for a slider with features that prevent progressive lubricant accumulation and thereby preserve the flyability of the slider.
The present invention relates to a slider for supporting a transducing head proximate a rotating disc. The slider includes a slider body having a disc opposing face bounded by a leading edge, a trailing edge, and first and second side edges. The slider body has a longitudinal axis. An air bearing surface is defined on the disc opposing face and the air bearing surface has a pad proximate the trailing edge. A trench is positioned adjacent to the pad with the trench being recessed from the air bearing surface at a step depth. A channel for flushing lubricant from the disc opposing face is positioned on the pad. The channel is recessed from the air bearing surface at a channel depth.
In one preferred embodiment of the present invention, the channel is comprised of a first channel and a second channel positioned on the pad wherein the first channel extends relative to the longitudinal axis at a positive angle and the second channel extends relative to the longitudinal axis at a negative angle.
In another preferred embodiment of the present invention, the pad is a center pad, and first and second side rails are positioned substantially along the first and second side edges of the slider body. The slider also includes a left side pad and a right side pad located at ends of the first and second side rails adjacent the trailing edge. A left side channel is positioned on the left side pad and a right side channel is positioned on the right side pad.